<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .wrap {
      width: 500px;
      height: 500px;
      background: green;
      display: grid;
    }

    .content {
      font-size: 30px;
      align-self: center;
      justify-self: center;
    }
  </style>
</head>

<body>
  <div class="wrap">
    <span class="content">123</span>
  </div>
</body>

</html>